Hydraulic double-acting metaldrawing press



Jan. 12, 1937.- wQ ERNST 2,067,265

HYDRAULIC DOUBLE ACTING METAL DRAWING PRESS Filed July 19, 1934 W A TTORIVEYJ Patented Jan. 12, 1937 PATENT orriciav nrnnanuo DOUBLE-ACTING METAL- DRAWING mass Walter Ernst, Mount Gilead, Ohio, asslgnor, by

mesne assignments, to The Hydraulic Press.

Corporation, Inc., Wilmington, Del., a corporation of Delaware Application July 19, 1934, Serial Ne. 736,062

15 Claims. (01.113-45) This invention relates to hydraulic presses and, in particular, to such presses arranged for drawing metal blanks into articles-of various shapes, the press-including means for clamping the metal blank'while the drawing operation is taking place.

One object .of my invention is'to provide a hydraulic double-acting press having a drawing piston and a clamping piston arranged to move I substantially sir'nultaneouslyinto position during the working stroke, until the blank is clamped,

whereupon the drawing piston continues the work of forming-the article.

Another object, is to provide a press of the above type wherein, after the drawing operation has been completed, the drawing piston first moves away from thework, which is held in place by the clamping piston until the drawin piston engages a member interconnecting it and s the clamping piston and carries the latter along with it and out of engagement with the blank and the formed'article.

Another object is to provide a hydraulic douhie-acting metal-drawing press having a clamp ing piston so arranged that the fluid discharged from the main cylinder during the working stroke .actuates the clamping piston before leaving the circuit.

Another object is to provide a hydraulic double-acting metal-drawing press having a main drawing piston and a clamping piston with piston heads so related in .area that the pull-back side of themain piston head has an area equal to the total area' of the clamping piston. head or heads, plus an additional area which is suffi- -'cient,.at the 'usual working pressure, to raise the force of gravity.

Another object is to provide a hydraulic douhie-acting metal-drawing'press wherein the pull- 40 back side of the drawingpiston is directly connected to the chamber above the clamping piston head, so that the clamping pistonwill be forced downward by the action of the fluid discharged from beneath the main drawing piston' head, and helddown for a period even after the fluid is reversed; until the drawing piston moves upward sufllciently to overcome the downward force exertedon the clamping piston whereupon it carries the clamping mechanism upward along 5 'with its own mechanism.

Another object is to provide a hydraulic double-acting metal-drawing press having a drawing" piston' and a clamping piston so arranged that the clamping piston is actuated by fluid dis-' 55 charged from'beneath the drawing piston in platen and clamping mechanism against the such a manner that both pistons move toward the work piece substantially together, means being provided for preventing the'drawing piston from moving ahead of the clamping piston, such as by providing choking means to retard the mo-. 5 tion of one piston relative to the other.

Another object is to provide hydraulic double-acting metal-drawing press of the above described type, wherein the clamping devices are provided with means for adjusting the clamping 10 pressure so as to exert a predetermined force upon the blank during the drawing operation.

Another object is to provide a hydraulic double-acting metal-drawing pressof theabove described type, wherein the fluid 'proceeding to- 5 ward or away from the main drawing cylinder will exert its pressure upon-the clamping piston, tending to hold it in a clamping position until the main piston itself pulls the clamping'piston away from the work piece by the application of 20 greater force.

Another object is to provide a hydraulic double-acting metal-drawing press having a main.

drawing piston and platen arranged to engage aclamping piston in. such a manner thatthe 25 clamping piston tends to push against the platen during the working stroke and be pulled away from the work piece by the platen during the return stroke.

In the drawing: 30 The flgure is a somewhat diagrammatic front elevation, partly in section, ofa hydraulic double-acting metal-drawing press arranged according to my invention, together with a simplified circuit for actuating it. /53 35.

Referring to the drawing in detail, the figure to a pipe 9, which may be connected to asuitable 45 source of compressed air in order to provide means for ejecting the flnishedarticle from the form-' ing portion 1 of the die 6. The blank or-metal plate' from which the article is to be produced is indicated by the reference numeral Ill.

The top member 3 or the pressis so formed as to include a main drawing cylinder II and a pair oi clamping cylinders l2 arranged on either side thereof. The number of the clamping and drawing cylinders H and I2 is immaterial, and it will 55 be understood that a greater or lesser number may be used as is most convenient for the partlcular'conditions encountered. The open ends Q of the cylinders H and I2 are closed by glands ward during .its working stroke. member 23 at its lowest eIJOSltiOIl comes to rest article. from the metal blank It held between them.

In a'similar manner the clamping plungers 28 pass through bores in the glands is and at their lower ends are attached to a tie member 22, which interconnects them. To the tie member 22 is secured the clamping member 23, as by the bolts 24. A blank holder 25 is placed upon the blank l and has an aperture 26, through which the die portion 23 may pass in proceeding down- The clamping on the opposite side of the blank holder 25 from the blank i5.

The double-acting main drawing piston head I 8 has a working face 21 and an' annular pullback or withdrawal face 28, whereas the clamping pistons 2i have piston head surfaces 219. In

the preferred form of my invention, the pull-back area 28 is equal to the combined area of the clamping head surfaces 29, increased by an amount sufiicient to enable it to lift the weight of its own mechanism plus that of the clamping mechanism at'the ordinary working pressures.

The platen i9 drivingly engages the tie member 22 along the flanged or shouldered portion 30 thereof so that the former will drive or move the latter in one direction. Accordingly, by this driving engagement, the platen l9 on its upward stroke will lift the tie member 22, together with 7 its associated plungers 2| and clamp member 23.

The weight of these parts is lifted by the additional area given to the annular pull-back surface 23 in excess of the area on the clamping piston heads-29. The portion of the main drawing cylinder l'l beneath the pull-back surface 28 is directly connected to the clamping cylinders I 2 by the passages 3! running therebetween.

From one of the clamping cylinders I2, the port 32 opens into the'conduit 33 leading to the two-way valve casing 34, from the opposite side of which the conduit 35 leads to the adjustable choke 36. Beyond it the conduit 31 joins the conduit'38 ina T connnection, leading to what is normally thesuction port 39 of the pump 49 when the press is exerting a working stroke. The pressure port 4| during the same operation leads, by way of the conduit 42, to the port 53, opening into the'space above the working surface 21 of the piston l 8 in themain cylinder ll.

Beyondthe junction of the conduits 31 and 38 v is the check valve 44, opening in the direction of the port 39. On the opposite side of the check workingjface 21 and the annular pull-back face 29 of the main piston head l8. In order to simplify the circuit these devices have not been shown,'since they form no part of the present aoemes invention. Due tothe diflerence in area mentioned, more oil will be discharged from the space above the piston surface 21 than from below the annular piston surface 28, and thisexcess fluid may also be discharged into the supply tank 46 by means forming no part of this invention.

The means for accomplishing this purpose may be obtained by the use of the main cylinder relief and by-pass valve shown in my previous hydraulic pump 20 is the donduit 41 which joins the check valve 68. The latter opens in the direction of one of the clamping cylinders l2 to the port 29, to which it leads by way of the conduit 50. Leading from the port of the other clamping cylinder 12 is the pipe 52, joining'the relief valve 53 having an outlet pipe 54 leading to the tank 66. 55 which is urged in a closing direction by-the spring 56. A pilot conduit 51 leads from the space above the'plunger 55 to the suction port 39 of the hydraulic pump 40. The purpose of this pilot line 57 is to apply pressure to the relief valve plunger 55 so that it cannot move upward and open the valve during the return stroke of the press (during which stroke the suction port 39 becomes a pressure port through the reversal of the fiow of the pump 30). This danger might otherwise occur when the relief valve 53 was set for low clamping pressure, in which case the fluid might pass out through the relief valve into the nk 46 and leave insufllcient pressure to lift the The pilot line 5? aprod 58 is urged in an upward direction by the coil spring 6|, engaging the valve head 59. The valve -rod extension -62 passes downward through the closure plug 53. Beyond the latter the valve rod extension 62 passes loosely through the bore- 68 in the arm 65 attached to the clamping tie member 22, as by the bolts 56. v The valve rod extension 62 is provided with an adjustable stop 61 which is adapted to be engaged by the arm 65 as the latter moves downward. This action inturn pulls the valve head 60 downward and closes the communication between the pipes 33 and 35 discharge fluid under pressure through the conduit 42 and the port 43 into the 'space above the piston head 3 within the cylinder l I.

This action causes the platen l9 tomove downward. At the sametime, the fluid displaced from the space beneath the piston head I8 is forced through the channels 3| into the clamping cylinders i2, causing theclamping plungers 2! likewise to move downward. To prevent the piston i 8 and the platen l9 from moving downward more rapidly than the clamping plungers 2| and the clamping member 23, the choke valve 35 is closed to such a point that the passage ofliquid is sum- The relief valve 53 is provided with a plunger,

I 7 2,067,265 .ciently impeded to force the. clamping plunger tie member 22 downward against the platen l9 by reason of the increased pressure within the clamping cylinders 12. The clamping member 23 and however, continues to move downward, forcing the central portion of the metal blank into the lower die portion 1 and forming the metal article. When the clamp-member has proceeded downward to the desired distance, the arm 65 of the clamping tie member 22 engages the stop 61 on the valve rod extension 62 ofthe two-way valve.

* .34, ulling it downward and interposing the valve head 60 between the ports leading to the conduits31and 35 respectively. The escape of fluid through the port 49 and the conduit 50 is prevented bythe check valve 48 which opens only in the direction of fluid passing in the direction of the pump 40 to the righthand cylinder l2.

Consequently .the only remaining means for the further escape of the fluid from the cylinders 12 and from the space beneath the piston head 18 in .the cylinder ll, now that the two-way valve 34 is closed, consists in the port 5| and pipe 52 leading from the lefthand cylinder I! to the relief' valve 53. When the pressure within the latter has increased to the. blow-off point, the plunger 55 rises against the,urge of the coil spring 56 and against the pressure exerted by the fluid or ming through the pilot line 51, discharging the subsequent fluid into the pipe 54 leading to the tank 48. The pressure within the clamping cylinders I2 thus forces the clamping member 23 firmly against the blank holder 25 and holds the blank l0 in a flrm'grip. The force with which the blank I0 is held may be adjusted byadiusting the loading of the plunger 55 of the relief valve 53.

The metal blank is now securely .held while the upper die member 20 continues to move downward into the lower die portion 1, performing the drawing operation.- This continued motion occurs because the area of the upper surface 21 of the piston head I8 is far larger than the area of the lower piston head surface 28.

When the drawing operation hasbeen com clamp the blank l0. Under the force of the pressure fluid against the annular surface 28 on the lower side of the piston head IS, the latter and the platen l9 move upward until the platen engages the shouldered portion 30 on the clamping tie member 22.

Due to the fact that the area of the lower annular surface 28 on. the piston head i8 is greater than the combined areas of the clamp ing piston heads 29, the piston head l8 will continue to move upward and the platen l9 will lift the clamping tie member 22 despite the opposing force exerted by the clamping plungers {The entire assemblyof the drawing and clamping mechanisms will. then move upward together at a rapid'rate, since the speed of the piston head I8 is augmented by the pressure of the fluid displaced by the upwardly moving clamping plungers 2|. The assembly will continue to travel until its top position is reached,

whereupon the pump 40 is shifted into its neutral position. Meanwhile the rising of the clamping tie member 22 and its arm 65 results in the release of the two-way valve rod 62. The two-way valve 34 then opens and permits the escape of pressure fluid therethrough from the clamping cylinders l2 and from the space beneath the piston head IS in the main drawing cylinder II. The metal article may now be ejected from the forming portion 1 of the die 6.

through the action of compressed air admitted through the pipe 9 and the bore 8 therein.

As has been previously mentioned, the fluid displaced from beneath the piston head l8 will be'of a lesser volume than the fluid displaced frorn'above the piston head l8, due'to the volume occupied by the piston rod |1.- The means for ejecting the surplus oil through a main cylinder relief and by-pass valve has been omitted, as previously stated, in order to simplify the circuit and because it forms no part of the present invention, being the subject of one of applicants previous patents. Fluid to supply a deficiency involume will, however, be admitted through the pipe .45 and the check valve 44 into the suction port 39 of the pump 40.

It will be understood that I desire to co prehend within my invention such modifications Having thus fully described my invention, 1

what I claim as new and desire to secure by 7 Letters Patent is:

1. In combination in a hydaulic press, a pump circuit for providing pressure fluid, a pressing cylinder, a. pressing plunger therein, a clamping cylinder, a clamping plunger therein, and means providing inter-flow of pressure fluid between said clamping plunger and one side of 'said pressing plunger, said pressing and clamping cylinders being so connectedand arranged that the fluid discharged from the pressing cylinder during the working stroke flows into the clamping cylinder and actuates the clamping plunger;

2. In combination in a hydraulic press, a pump circuit for providing pressure fluid, a pressing cylinder, a pressing plunger therein, a clamping cylinder, a clamping plunger therein, and means providing inter-flow of pressure fluid between said clamping plunger in said clamping cylinder and one side of said pressing plunger in said pressing cylinder, the last-mentioned side of said pressing plunger having an area greater than the head area of said clamping plunger.

3. In combination in a hydraulic press, a pump circuit for providing pressure-fluid, a pressing cylinder, a double-acting pressing plunger therein with its opposite sides connected to said pump circuit, a clamping cylinder, a clamping plunger therein, and means providing for the constant and uninterrupted inter-flow of pressure fluid between said clamping'plunger in said clamping cylinder and one side of said pressing plunger in said pressing cylinden; 4. In combination in a hydraulic press, 'apump circuit tor -providing pressure fluid, a pressing cylinder, 9. pnessing plunger therein, a platen connected thereto, a pair of clamping cylinders adjacent said pressing ,cyllnder, a clamping plunger in each clamping cylinder, a clamping adjacent said pressing cylinder, a clamping plunger in each clamping cylinder, and a clamp-, ing member interconnecting said clamping plungers to be operated thereby, said platen and said clamping member being adapted to drivingly engage one another by a contact in one direction only.

6. In combination in 'a, hydraulic press, apump circuit for providing pressure fluid, a pressing cylinder, a pressing plunger-therein, a platen connected thereto, a pair'of clamping cylinders adjacent said pressing cylinder, a clamping plunger in each clamping cylinder, a clamping member interconnecting said clamping plungers to be operated thereby, said platen and said clamping-member being adapted to drivingly engage one another, means providing free interflow of pressure fluid between said clamping plungers and said pressing plunger, and means providing restricted flow of fluid between said clamping plungers and said pump circuit.

7. In combination in a hydraulic press, a double-acting pressing plunger, a platen connected thereto, a clamping plunger, a clamping member operated thereby, said platen and said clamping member being adapted to engage one another, and means for restricting the discharge of pressure'fluid from around onev of'said plungers,

whereby to maintain 'said platen and said clampwith its opposite sides connected to said pump circuit, a platen connected) thereto, a clamping cylinder, a clamping plunger therein, a clamping ,memberoperated thereby, said platen and said clamping member being adapted to drivingly engage one another, and means providing interflow of pressure fluid between said. clamping plunger and one side of said pressing plunger, the last-mentioned side of said pressing plunger having an area greater than the head area of said clamping plunger by an 'amount suflicient to enable the pressure fluid to' retract said pressing plunger and said clamping plunger against the gravitational and other opposing forces exerted thereon.

10. In combination in a hydraulic press, a

double-acting pressing plunger,

said pressing plunger.

double-acting pressing plunger, a clamping plunger, means providing inter-flow'ofpressure;

fluid between said'clamping plunger and one side of 'said' pressing plunger, and valve means adapted to control the flow of fluid with respecteto the space around said clamping plunger, 'saidvalve means being operated by-themotion of one of said plungers.

11. In combination in a hydraulic press, a double-acting pressing plunger, a clamping plunger, means providing inter-flow of pressure fluid between said clamping plunger and one side of said pressing plunger, and valve means adapted to control the flow of fluid with respect to the space around said clamping plungeiysaid valve means being. operated by the motion of' said clamping plunger.

12. In combination in a hydraulic press, a a clamping plunger, means providing inter-flow of pressure fluid between said clamping plunger and one side of said pressing plunger, valve means adapted to control the flow offluidwith respect to the space around said clamping plunger, and escape valve means adapted to open at a predetermined pressure and releasefluid from the space around 13. In combination in a hydraulic I press; a double-acting pressing plunger, a. clamping plunger, means providing inter-flow of pressure fluid between said clamping plunger and'one side of said pressing plunger, valve means adapted to control the flow of'fluid' 'with respect to the i space around said clampin g plunger, and escape valve means adapted-to open at a predetermined pressure and release fluid from the space around said pressing plunger 'while said plunger-operated valve remains closed.

14. In combination in a hydraulic press,- a

double-acting pressing plungeng aplatencone nected thereto, ,a clamping plunger, a clamping I member operated thereby, means providing inter- *flow ,of pressure fluid between said clamping plunger and one side of said pressing plunger, and

' escape valve means associated with said clamping plunger to release the presure fluid from the space therearound when the clampingpre'ssure thereof reaches a predetermined'amount.

plunger and one side of said pressingplunger, a

tie member releasablyinterconnecting said press- -ing plunger and said clamping plunger, and escape valve means associated with said clamping plunger to release the pressure fluid from the space therearound when the clamping pressure thereof reaches a predetermined amount, said tie member being arranged to permit said platen to cont ' wAn'rna ERNST.

ue its motion after said clamping member has reached its clamping'position. 

